This project will use sequencing by hybridization (SBH) to develop a faster, more economical method for sequencing and mapping. Current DNA sequencing procedures almost universally require gel electrophoresis of DNA fragments and are cumbersome and slow. SBH promises to produce rapidly large amounts of sequence information due to the parallel nature of the analysis and is well suited for sequencing cDNAs or partial sequencing of amplified DNA to facilitate mapping. Enriched stable isotopes will be utilized as labels for SBH to demonstrate the basic advantages of such labels and to show the multiplexing feasibility. We have demonstrated that stable isotopes function as both DNA and oligonucleotide labels and that resonance ionization spectroscopy can offer a very fast method for the detection of surface-bound DNA. During Phase I we will be evaluating two potentially viable detection techniques for rapid sequencing and mapping using genosensor matrices: sputter-initiated resonance ionization spectroscopy (SIRIS) and laser atomization RIS (LARIS). Measurements will be made on nylon surfaces, onto which DNAs have been attached, to identify positively hybridized and unhybridized sites and to determine the sensitivity, efficiency, background, spatial resolution, and speed and the interrelationships and trade-offs among them.